I think this might be relevant

On the scale of things, I think this rate's a "who the fuck cares?".

I don't really care if cousins get married. I don't really care if they have kids together. I do care if they have birth defects and we should do things medically responsible to reduce or eliminate birth defects, but the whole cousin thing doesn't really bother me as long as there's no external pressure (like British royalty or stereotypical Southern Hicks).

Who is really that bent out of shape on this and why should we care?

British teeth explained.

An unfortunate aspect of Pakistani culture that has carried over to the UK.

Families would marry within the family to keep their wealth within the family.

Unfortunately after successive generations, this can cause serious problems.

ITT: Blatant ableism disguised as concerns.

Should you be allowed to have children if you are a known carrier of some bad but not inmediatly deadly risk gene like fragile x, chorea huntington, mucoviszidosis, diabetes 1 (let's ignore the worsening of fragile x and chorea huntingtion across generations for a moment)? Should you be allowed to have children if you have trisomie 21, or some other mental disability? If you say no i think you are ableist and can't comprehend that people with special needs are still people that can be happy and can have desires. If you say yes why can't two cousins have a child? What if they have two forms of birth control and just want to fuck? What if they are the same sex? I my experience most people who are against two cousins having sex do not give a flying fuck about some theoretical chile but just think it's icky. Which is a fair feeling you are allowed to have but should not be basis for a law.